Field
The present invention relates to wireless communication, and more particularly, to a method and an apparatus for establishing maximum transmission power PEMAX and signaling the maximum transmission power to UE in a situation in which the UE is dually connected to a plurality of base stations.
Discussion of the Background
UE can perform wireless communication through one or more base stations among base stations constituting at least one serving cell. This is referred to as dual connectivity. In this case, one of a plurality of base stations which are physically or logically divided can be referred to as a central base station (alternatively, serving base station) and the other one can be referred to as a small base station (alternatively, non-serving base station).
The base station can use power headroom information of the UE in order to efficiently use resources of the UE. A power control technology is an essential core technology for minimizing interference elements and reducing consumption of a battery of the UE in order to efficiently distribute the resources in wireless communication.
When the UE provides the power headroom information to the base station, the base station can estimate maximum uplink transmission power which can be allocated to the UE. Accordingly, the base station can provide uplink scheduling such as transmission power control, modulation and coding levels, and a bandwidth to the UE within a range not to departing from a limit of the estimated maximum uplink transmission power.
When a scheduler is positioned in individual base stations while the UE simultaneously performs uplink transmission through two base stations, a scheduling situation between the base stations cannot be verified due to a difficulty in exchange of scheduling information between the base stations.
A base station in which the dual connectivity is configured configures the maximum transmission power PEMAX so as to prevent the maximum transmission power PEMAX from being over transmission power of a maximum capability of the UE at the time of configuring the maximum transmission power PEMAX and dedicated signaling is requested to the UE.